Earlier on Thursday, another car driven by a bomber targeted a convoy of three armoured vehicles in the centre of the capital, killing one person and wounding at least eight Iraqi civilians.
Eight civilians were also wounded when an unidentified driver rammed his explosives-laden car into the three-vehicle convoy.
One of the armoured cars, vehicles generally used by private security firms, was slightly damaged, according to a policeman at the scene on Thursday.
Those hurt were in the vicinity of the attack at the time and included one woman, police added.
The attack occurred at about 9.30am (0530 GMT) in a commercial area of eastern Baghdad.
US soldier killed
In another incident, a roadside bomb hit a US army patrol in northern Baghdad on Thursday, killing one soldier, the US military said.
The attack occurred at about 8.15am (0415 GMT), said Sergeant 1st Class David Abrams, a military spokesman.
The victim was not immediately identified pending notification of his relatives.
The attack raised to at least 1944 the number of US military personnel who have died since the beginning of the Iraq war in March 2003, according to Pentagon figures.
Elsewhere in the capital, three civilians and one policeman were shot dead in three separate incidents, security officials said.
Late on Wednesday, a retired Iraqi police general and his two-year-old daughter were killed in a drive-by shooting in the northern city of Kirkuk, police said on Thursday.
Iraqis cry over the body of a two-
year-old girl killed in Kirkuk
The wife of retired Brigadier-General Nabil Sharaf al-Din was wounded in the attack.
The general, who headed the city's transport police until six months ago, and his family were ambushed while driving in the centre of the town, said police Colonel Adel Zain al-Abedin.
On Thursday morning, an unidentified armed group shot dead five Iraqi Oil Ministry security guards who were driving to the northern city of Kirkuk on Thursday, police said.
Lieutenant Jawaad Abdullah said they were shot in the town of Uthaim, south of Kirkuk. The attack came a day after a car bomb critically wounded six security guards for the state-owned North Oil Company in Kirkuk, an oil centre.
Sunnis to vote
Meanwhile, Iraqi member of parliament Mishaan al-Juburi told Aljazeera that the US offensive against predominantly Sunni towns in the central Anbar province was a repetition of similar tactics used ahead of the January 2005 elections.
Mishaan al-Juburi criticised the
US offensive in central Anbar
''What we fear most in the governorates that contain mixed residents is the targeting of Sunni Arab neighbourhoods, in order to prevent Sunnis from attaining the two-thirds of the consensus required to vote down the [constitution] at the referendum," he said.
He lauded the role of the United Nations in pressing the Iraqi parliament to reverse last-minute electoral law changes.
The changes would have made it impossible for the draft constitution to be voted down in the 15 October referendum.
Source: Aljazeera + Agencies